The present invention relates generally to Java computing environments and, more particularly, to techniques for providing command control capabilities for receivers operating in Java TV environments.
Digital television (DTV) is the transmission of television signals using digital rather than conventional analog methods. Analog transmission is in the form of a variable wave. Digital transmission consists of an electrical pulse which has two possibilities: on and off (or positive and negative), which are represented by a one and a zero (this is binary data, the same type of information that a computer understands). Because a digital signal does not fluctuate, but is either perfectly intact or totally absent, a digital transmission is more precise than an analog transmission. Although both signals are transmitted in the same basic way and have the same range, they behave differently at the limits of their ranges. An analog signal degrades over distance and may be barely detectable at the further reaches of the broadcast area—this is why the signal from a distant radio station fades in and out. As the signal reaches the farthest limits of its range, the signal-to-noise ratio (SNR) decreases and the quality of the broadcast suffers, although the range remains the same. In comparison, when the SNR decreases in a digital signal, the quality of the broadcast does not degrade, but the range shrinks (this is called the cliff effect). Accordingly, the advantages of DTV over analog TV include: superior image resolution (detail) for a given bandwidth, smaller bandwidth for a given image resolution, compatibility with computers and the Internet, interactivity, superior audio quality, consistency of reception over varying distances, and capacity for multicasting.
Conventional standards, NTSC, PAL, and SECAM, specify analog transmission. However, both the audio and video components of a television signal can be transmitted in digital form. Because much more data can be sent digitally, a digital transmission will allow, depending on the display format chosen, either a dramatically improved resolution and sound quality in the case of high definition television (HDTV), or simultaneous broadcasts (multicasting) of up to five programs in the case of standard definition television (SDTV). Another SDTV option, known as datacasting, is the transmission of data such as games, still pictures, and other material while the viewer is watching a program. Datacasting might allow, for example, someone watching a baseball game to choose a different camera angle or to select a display of player or team statistics.
The attraction of DTV is not only the clearer picture and higher quality sound, but the ability to interact with the television program that is being broadcast. Interaction could include a viewer playing a game while watching an educational program, downloading a recipe from a favorite cooking show, or choosing a program to watch from an electronic program guide (EPG). An EPG is an onscreen television guide that displays channel and program information at no extra cost to the viewer. In DTV, the EPG is sent as a separate data packet in the MPEG-2 transport stream.
There are two types of EPGs: text-based and multimedia. A text-based EPG is similar to a printed television guide. A multimedia EPG allows the viewer to choose and record a program once, daily or weekly at the touch of a button on the remote, sort through movies by theme, review top national and world news stories, and access comprehensive coverage of news, weather, sports, and entertainment stories. A typical multimedia EPG includes channel grids that contain present and future television programs along with a video window that displays a current broadcast from a selected channel and a brief description of the program.
Another recent development is the production of Digital Versatile Disc (DVD) for general use. DVD is an optical disc technology that is expected to rapidly replace the disc (as well as the audio compact disc). The DVD holds 4.7 gigabytes of information on one of its two sides, or enough for a 133-minute movie. With two layers on each of its two sides, it will hold up to 17 gigabytes of video, audio, or other information. (Compare this to the current CD-ROM disc of the same physical size, holding 600 megabytes). The DVD can hold more than 28 times as much information.
DVD-Video is the usual name for the DVD format designed for full-length movies and is a box that will work with your television set. DVD-ROM is the name of the player that will (sooner or later) replace your computer's CD-ROM. It will play regular CD-ROM discs as well as DVD-ROM discs. DVD-RAM is the writable version of DVD-ROM. DVD-Audio is a player designed to replace the compact disc player. DVD uses the MPEG-2 file and compression standard. MPEG-2 images have four times the resolution of MPEG-1 images and can be delivered at 60 interlaced fields per second where two fields constitute one image frame (MPEG-1 can deliver 30 noninterlaced frames per second). Audio quality on DVD is comparable to that of current audio compact discs.
DVD-Video Discs usually contain an application that presents menus to the viewer, and allows him to control aspects of the video presentation. For example, the applications allow the viewer to jump to a specific scene, control subtitling, select camera angles, select audio tracks, etc. These applications also display graphic images on the screen, and allow highlighting of choices and navigation using the remote control. DVD control applications are written in DVD Assembly Language.
The conventional Java-based interactive Digital TV environment can provide the user with the same command control capabilities as provided in the DVD environment. However, the conventional Java-based interactive Digital TV environment does not recognize DVD assembly language. As a result, conventional environments suffer many drawbacks. By way of example, users of Video on Demand (VOD) do not have the capability to pause, rewind, fast forward, etc. It should be noted that the consumers accessing Video on Demand movie sites usually are doing so over high-speed or broadband connections, such as through cable modem services, or Digital Subscriber Loops (DSL), which are becoming more popular.
Accordingly, an improved digital TV environment is needed.